Gravity flow discrete article gas flow isolated thermal treatment device and method

ABSTRACT

Small articles such as springs are heat treated as they flow downward by gravity through a straight cylindrical tube. The tube need not be cylindrical or straight and means to assist gravity may be provided. The articles are heated by hot air or other gas introduced to said tube through apertures in its walls and which flows through portions of the tube at high velocity. Hot air thus introduced is withdrawn through other apertures in the walls of the tube in a manner to prevent heat loss by exhaust of the hot air at either end of the tube or by introduction into the tube of ambient cool air at either end of the tube.

11] 3,850,572 [451 Nov. 26, 1974 United States Patent Andrus [5 1GRAVITY FLOW DISCRETE ARTICLE GAS 3,199,854 8/1965 lpsen............432/134 FLO ISOLATED THERMAL TREATMENT 3,351,329 11/1967 Thomas 432/72DEVICE AND METHOD 3,467,366 9/1969 Westeren etal................:::...

[76] Inventor: Everett Howard Andrus, Rt. No. 4, Primary Examiner-JohnJ. Camby Watertown, Wis. 53094 Mar. 8, 1974 Attorney, Agent, orFirm-John M. Diehl 221 Filed:

ABSTRACT Small articles such as springs are heat treated as they flowdownward by gravity through a straight cylindrical tube. The tube neednot be cylindrical or straight and means to assist gravity may beprovided. The articles are heated by hot air or other gas introduced tosaid tube through apertures in its walls and which 21 Appl. No.2 449,364

26 5 M M ll 2 H n i fl 4 2 4 ,19 6 4 4 l 1 2 t 4 3 M 4% 4 U ZHU F/ a 4m4 m W .C n r H .e m m L .f C G m s e U .IF .1. 2 8 5 55 .1 [.1

flows through portions of the tube at high velocity. Hot air thusintroduced is withdrawn through other apertures in the walls of the tubein a manner to prevent heat loss by exhaust of the hot air at either endof the tube or by introduction into the tube of ambient cool air ateither end of the tube.

1,643,775 9/1927 Ke11eher................................ 432/641,725,129 8/1929 Carpenter et 432/64 2,253,897 8/1941Doderer................................ 432/64 10 Claims, 20 DrawingFigures PAIENI nsv 2 61914 SHEET 02 0F 10 PATENTEL 3.850.572

saw on or 10 Fig. 5.

Pmmmm I I 3,850,572

SHEET 0? or 10 END PLATE TUBE LENGTH Fig. /8.

GRAVITY FLOW DISCRETE ARTICLE GAS FLOW ISOLATED THERMAL TREATMENT DEVICEAND METHOD I BACKGROUND OF THE INVENTION 1. Field This invention relatesto a furnace or oven or heating apparatus and more particularly to suchapparatus for heat treating small articles by passing heated airthereover.

2. Prior Art The invention is an improvement over the disclosures of thefollowing patents:

US. Pat. Nos. 3,351,329 and 3,467,366 describe use of venturi apparatusto provide isolation of the atmosphere within the furnaces describedtherein from the ambient atmosphere, unlike the device of the presentinvention.

The other above listed patents likewise describe various means forproviding isolation of the atmosphere within a furnace from the ambientatmosphere; each is distinguished from the apparatus of the instantinvention as will be apparent from the following detailed description.

SUMMARY AND BACKGROUND Small articles such as springs, fasteners, twistdrills and the like have traditionally and conventionally been heattreated by placing the articles in a perforated metal box and placingthe box in a furnace into which heated air or other gas is introduced orby placing the articles in a rotating drum provided with heated air orother gas in the interior thereof.

Such articles or devices (especially springs and many fasteners) areoften characterized by a tendency to become entangled when placed helterskelter into a container. Normally hand labor is required to separatesuch devices which have been heat treated in bulk in the manner of theprior art and generally an excessive and evenstupendous cost factor isthereby added to the overall cost of producing the part. For example, ithas been not uncommon for the' cost of carrying out this single step inthe manufacture of a spring to outweigh or be larger than the total ofall other costs in the manufacture of the spring, including cost ofmaterials, cost of original manufacture of the spring, all costs oftrans-' portation and even the cost of installing the spring in thefinal device for which it is destined which can often be doneautomatically by robot-type machinery. That which is true for suchsprings is also true for many other metal wire parts and spring steelfasteners and fastener parts.

Generally throughout the remainder of this specification reference willbe had to springs. But it is to be understood that such reference tosprings is intended to include other small articles or parts to whichthe invention may apply, including for example but not limited to springsteel fasteners, spring steel fastener parts, twist drills, bifurcatedrivets and hollow rivets, the heat treating of which is required as astep in the manufacture thereof.

The device of the present invention is normally adapted to be locatedimmediately adjacent a spring coiler, that is, a spring manufacturingmachine, so that as each spring manufactured by the spring coiler isejected from the coiler or falls from the coiler it is introduced bygravity or by the force of the ejection from the machine into the deviceof the invention.

In the device of the invention a tube is provided in which the springstravel vertically downward or at an angle downwardly. The tube ispreferably straight and cylindrical but for parts other than coilsprings may have any other suitable configuration. Springsform a columnor stack of springs within the tube of the device, the lowermost springbeing supported by a release mechanism provided at the lower extremityof the device and the remainder of the springs in the column or stackbeing supported by one another. The release mechanism releases a springfrom the bottom of the heat treating device of the invention for eachspring introduced at the top of the device so that the rate of releaseof the springs from the heat treating device exactly corresponds to therate of introduction of the springs to the heat treating device.

Generally the springs travel downwardly through the central tube of thedevice due to the force of gravity acting thereon but in certaininstances, generally in those instances wherein the tube is relativelylong and inclined at a relatively small angle to the horizontal, meansto vibrate the tube or to vibrate the entire device and thereby vibratethe tube may be provided to assist gravitational force to cause thesprings to .travel downwardly therethrough.

Objects Itis therefore an object of the invention to provide an improvedheat, treating device.

Another object is such animproved device thereof.

Another object is such a device wherein the parts travel in a columnthrough a tubular portion of the device. v Another object is such adevice wherein heating of the articles to be heat treated is provided byhigh velocity hot gas traveling in said tubular portion.

Another object of the invention is such a device.

wherein heating of each article to the temperature of heat treatmentoccurs very rapidly and very near the point of entry of the article intothe device.

Another object of the invention is such a device wherein the ends ofsaid tubular portion are open to the ambient atmosphere and yet no heatloss or gain and no exchange of said heated. gas with the gas of theambient atmosphere takes place- Another object is such .a device whichmaybe made relatively short.

Other objects will become apparent from the drawings and from thefollowing detailed description.

FIG. 1 is an elevation from the front of a preferred embodiment;

FIG. 2 is an elevation from the rear of the embodiment of FIG. 1;

FIG. 3 is a cross-sectional view takenon lines 3-'3 in FIGS. 5, 6 and 7;

for heat treating small entangleable parts without entanglement FIG. 7is a cross-sectional view taken on lines 77 in FIGS. 1, 2, 3 and 4;

FIG. 8 is a schematic view of an embodiment corresponding to theembodiment of FIGS. 1-7;

FIG. 9 is a schematic view of another embodiment;

other embodiment of release mechanism for the device;

FIG. is a partially cross-sectional elevation of a modification of theembodiment of FIG. 14;

FIG. 16 is a plot of temperatures in bayonet tubes under variouscircumstances;

FIG. 17 is an elevation of a spring which may be heat treated in thedevice of the invention;

FIG. 18 is an elevation of another spring which may.

be heat treated in the device of the invention;

FIG. 19 is a plot of the relationship between time and temperature for acertain spring traveling through the device of the invention; and

FIG. 20 is a plot of the relationship between time and temperature foranother spring traveling through the device.

DESCRIPTION Referring now to FIGS. 1-7, housing 20 may have supportsegment 21 attached thereto. Support segment 21 may be rotatablyattached to support segment 22 by means not shown and support segment 22may be attached to collar 23 which may be slidably received on supportpost 24 and may be retained at any desired vertical position on post 24by tightening set screw 25;The angle of support of housing 20 withrespect to vertically extending post 24 may be selected and retained byinserting pin or bolt 26 through one of holes 27 in segment 22 andthence into one of holes 28 in segment 21. If the distance between eachof holes 27 is made somewhat different than the distance between each ofholes 28, a very great number of different angular positions of housing20 with respect to post 24 may be selected by suitably judiciousselection of one of holes 27 and one of holes 28 through which to placepin 26.

Housing 20 may be provided at its ends with end plate members 30 and 31and may be provided with interiorly extending tubular member 32sometimes hereinafter referred to as shroud tube or housing tube 32which may have its ends attached respectively at 33 and 34 to end plates31 and 30.

Disposed within and extending through housing tube 32 there may beprovided bayonet tube .13 which may extend beyond upper end plate 30 atits upper end 35 and may extend below lower end plate 31 at its lowerend 36 and may have attached thereto a plurality of plates and bafiles,respectively upper end plate 40, baffle 41, baffle 42, baffle 43, baffle44 and lower end plate 45. In the event that housing tube 32 iscylindrical as in the embodiment shown, each of these end plates andbafiles may be annular in shape and may be attached at its innerperipheral edge securely to tube 13,

as by welding, and may be slidably fitted in the interior of tube 32 atits outer peripheral edge. As may be seen, bayonet 46 may readily bereplaced with another bayonet having a tube with a smaller or largerinternal diameter to treat objects having smaller or larger diametersrespectively. This may be accomplished in only a few minutes by removingscrews 49, then removing holddown plates 48 and plugs 47, then slidingout the bayonet contained in tube 32 and sliding in another bayonet andthen replacing plugs 47, plates 48 and screws 49. The internal diameterof tube 13 is preferably slightly greater than that of objects to betreated therein. The assembly consisting of tube 13, end plates 41 and45 and baffles 42, 43 and 44 is indicated generally as bayonet orbayonet assembly 46. Bayonet 46 may be retained within housing tube 32and housing 20 by providing an insulating plug 47 at each end andproviding holddown plates 48 attached respectively to end plates 30 and31 with screws 49 to act against plugs 47 which in turn bear againstbayonet end plates 40 and 45. Annular insulating plugs '47 may beslidably received within the bore of tube 32 and slidably received onthe exterior of tube 13 adjacent ends 36 and 36 respectively.

Also provided within housing 20 are heater tube 50 containing electricheating element 51 and tube 55 to provide for flow of air as hereinafterdescribed.

Tube 50 may be provided with ends 57 and may be attached to tube 32 asby welding: at 58.

Tube 55 may have ends 55'. Tube 55 may be referred to as abalance tubefor lack of some better term. Heating element 51 may be supported withintubes 50 by conventional means which for simplicity are not shown.

The space within housing 20 which lies outside of tubes 32, 50 and 55,may be filed with insulation 56.

Although each of tubes 13,32, 50 and 55 are shown as being round, thatis, cylindrical, any one or more of these tubes may have any othersuitable cross-sectional shape such as that of a sqaure, triangle,hexagon, octagon or any regular or irregular polygon.

Housing 60 may be attached to housing 20 and may contain fan or blowerindicated generally as 61 which comprises blades 62, 63, 64 and 65attached to shaft 66 driven by electric motor 67 which may be mounted onbase plate 68 which may be attached to housing 60 with screws 69.

Electrical heating element 51 is supplied with electricity throughelectrical conductors 52 from a source indicated as 53 and may beinsulated or may extend through insulating bushings 54 received in wallsof tube 50 and housing 20 respectively.

Device 70 which may have the fonn of a hollow cylinder or other annularform, as shown, may be disposed adjacent end 35 of bayonet 46 so thateach article or spring as it enters the interior of tube 13 must passthrough the center thereof. Device 70 may be suitably constructed toindicate the presence of each spring or article as it passestherethrough. For example, device 70 may provide an electrical ormagnetic field, one of the properties of which, such as capacitance orinductance, may be changed by a spring or other article passing throughdevice 70, and device 70 may generate and emit a signal in response tosuch change to indicate the presence of an article therein. This signalmay be transmitted by conductors, not shown, to conventional apparatus,not shown, which may send another signal, in

response to such signal, to the release mechanism indicatedschematically at 71 which may be attached, adjacent to bottom end 36 ofbayonet 46, to plate 72 which may be attached to housing 20, forexample, with screws 73. Release mechanism 71 is shown and discussed indetail in connection with FIGS. 13, 14 and 15.

Passage 80 for air to pass (as indicated by arrows 81) from housing 60to the interior of tube 50 may comprise outlet port 82 in housing 60,inlet port 83 in housing 20, wall 84 and scroll wall 85 connected toopening 86 in the wall of tube 50.

Passages 89 and 90 respectively for air to pass from the interior oftube 50 to the interior of tube 32 (as indicated by arrows 91) may beprovided by contiguous matching or registering openings in the walls oftubes 50 and 32, as shown, supplemented with walls 92 which may beattached by welding as at 93.

Air may be withdrawn through tube 32 in the balance tube 55 (asindicated by arrows 95) through port 96 provided by matching orregistering contiguous openings in the walls of tubes 32 and 55, asshown,-and by welldments 97 as shown.

Air may be withdrawn from balance tube 55 into tube 32 as indicated byarrows 98 and thence from tube 32 into fan housing 60 as indicated byarrows 99, respectively through port 100 provided between balance tube55 and shroud tube 32 by contiguous registering openings therein andweldments 97 and through fan inlet port 101 provided by matchingcontiguous openings in the walls respectively of tube 32, housing 20 andhousing 60, as shown.

End plate 40 and baffle 41 define a first annular space disposed betweenthe interior of tube 32 and the exterior of tube 13. Baffles 41 and 42define a second annular space between the interior surface of tube 32and the exterior surface of tube 13. Baffles 42 and 43 define a thirdannular space between tubes 13 and 32. Baffles 43 and 44 define a fourthannular space between tubes 13 and 32. Baffle 44 and end plate 45 definea fifth annular space between tubes 13 and 32. Apertures are provided inthe wall of tube 13 communicating the interior of tube with each of saidfive spaces and apertures are provided as shown in baffles 42 and 43.Bayonet 46 is shown schematically in FIG. 8 wherein the air flow throughsaid apertures and into and out of said spaces and within the interiorof tube 13 is more fully described.

Referring now to FIG. 8, bayonet 46 of FIGS. 1-7 is shown schematically,comprising tube 13, end plates 40 and 45, baffles 41, 42, 43 and 44 andhaving inlet end 35 and outlet end 36. Heater 51 may correspond toheater 51 of FIGS. 1-7 and blower 61' may correspond to fan or blower 61of FIGS. l-7. For simplicity shroud tube 32 is not shown. The fiveannular spaces lying be tween the exterior of tube 13 and the interiorof tube 32 described as defined by end plates 40 and 45 and baffles 41,42, 43 and 44 in connection with FIGS. 1-7 are indicated in FIG. 8schematically by arrow 111 indicating air withdrawn from said firstspace, arrow 112 indicating air introduced into said second space,arrow.

correspond respectively to heater 51 and blower 61 of Y FIGS. 1-7. Thetube of bayonet 146 is indicated as 147 113 indicating longitudinal airflow through said third space, arrow 114 indicating withdrawal of airfrom said fourth space and arrow 115 indicating introduction of air tosaid fifth space. Flow through balance tube 55 is indicated at line 116.

As indicated by arrows 121, air is removed from theinterior of tube 13through apertures 131 into the first space. As indicated by arrows 122,air is introduced from the second space through apertures 132 in thewall of tube 13 and in baffle 42 from said second space into theinterior of tube 13 and into the third space. As indicated by arrows124, air is removed from the interior of tube 13 and from the thirdspace into the fourth space through apertures 134 in the wall of tube 13and in baffle 43. -As indicated by arrows 125, air is introduced fromsaid fifth space into the interior of tube 13 through apertures 135.

As a critical feature of the method and device of the invention, thesize of each of the first, second, third,

fourth and fifth spaces and the number of apertures and size ofapertures provided in the wall of tube 13 to provide communicationbetween each of said spaces and the interior of tube 13 and the size andnumber of apertures in baffles 42 and 43 isso chosen and adjusted as toprovide for zero or nil outflow of gas from the interior of tube 13 atinlet end 35 as indicated by arrow and to provide for zero or nil inflowof ambient atmospheric air into the interior of tube 13 at end 35 asindicated by arrow 141 and likewise to provide for zero or nil outflowof air from the interior of tube 13 at end 36 as indicated by arrow 142and to provide for zero or nil inflow of ambient atmospheric air intothe. interior of tube 13 at end 36 as indicated by arrow 143.

A plurality of articles such as springs 105 may be introduced intobayonet 46 atend 35 as. indicated by arrow 106 and after travelingthrough tube 13 and being suitably heat treated may emerge as indicatedat arrow 107.

tube provided with end plates and baffles, as in the case of bayonet 46,and heater 51" and blower 61' may and is provided with end plate 148,baffles 149, 150, 151, 152 and 153 and end plate 154. Articles suchasspring 108 may enter either end of tube 147 and travel therethrough tobe heat treated as indicated by arrow 109. 9

End plate 148 and baffle 149 define a first space into which air maybeintroduced, as indicated by arrow 155. The air may then flow throughapertures 156 into the interior of tube 147 as indicated by arrows 158.Baffles 149 and define a second space from which air may be withdrawn,as indicated by arrow 159 and into which air may be introduced from theinterior of tube 147 through apertures 160 as indicated by arrows 161.Baffles 150 and 151 define a third space into which air may flow throughapertures 162 in bafile 151 as indicated by arrows 163 and travellongitudinally as indicated by arrows 164 and enter into the interior oftube 147 through apertures 165 as indicated by arrows 166. Baffles 151and 152 define a fourth space into which air may be introducedas'indicated by arrow 167 and from which air may flow into the interiorof tube 147 through apertures 168 as indicated by arrows 169 and mayflow through apertures 162 into the third space as indicated by arrows163. Baffles 152 and 153 define a fifth space from which air'may bewithdrawn as indicated by arrows 170 and into which air may flow fromthe interior of tube 147 through apertures 171 as indicated by arrows172. Baffles 153 and end plate 154 define a sixth space into which airmay be introduced as indicated by arrows 173 and may flow into theinterior of tube 147 through apertures 174 as indicated by arrows 175.

Nil or zero flow of ambient air into tube 147 at each end is indicatedby arrows 176 and nil or zero flow of gas from the interior of tube 147outward to the ambient atmosphere is indicated by arrows 177, the nil orzero flow indicated by arrows 176 and 177 being accomplished by suitablechoice of the size of each of the spaces defined by the end plates andbaffles and provision of a suitable number of apertures of suitable sizeand spacing in tube 147 and in baffle 151 communicating between saidspaces and the interior of tube 147.

Suitable manifolding to provide the hereinabove described flow fromblower 61 and heater 51" into and out of the various defined spaces(such as is provided in the embodiment of FIGS. l-7 by balance tube 55)is indicated by lines 178.

Referring now to FIG. 10, a bayonet 246 is provided which may be similarto bayonet 146 or bayonet 46 and may comprise a tube 213 having endplates 214 and 215 and baffles 216, 217, 218, 219 and 220 which maydefine spaces from which air is withdrawn as indicated by arrows 221 orintroduced as indicated by arrows 222 or within which air may merelytravel longitudinally as indicated by arrows 223. Heater 51" and blower61" may correspond respectively to heater 51 and blower 61.

Communicating flows between said spaces and the interior of tube 213 and.flow through baffle 219 are indicated by arrows which (unlike those ofthe embodiments of FIGS. 8 and 9) are unnumbered, said flows takingplace through apertures in the wall of tube 213 and in baffle 219 which(also unlike those of FIGS. 8

and 9) are unnumbered.

As with the embodiments of FIGS. 8 and 9, suitable choice of thelocation of the baffles with respect to each other and with respect tothe end plates and suitable design of size and number and location ofapertures provides nil flow from the ambient atmosphere into theinterior of tube 13 as indicated by arrows 230 and nil flow outwardlyfrom the interior of tube 13 to ambient atmosphere is indicated byarrows 231.

An object to be heat treated such as a small fastener 232 may beintroduced into tube 213 of bayonet 246 through either end and maytravel therethrough in either direction as indicated by arrow 233.Manifolding in the manner of balance tube 55 or such manifolds as areindicated by lines 178 in FIG. 9 may be provided as indicated by lines234 in the embodiment of FIG. to provide suitable flow to and from thedefined spaces and to and from the blower and heater.

The embodiments of FIGS. 8, 9 and 10 show that the relative positions ofspaces from which air is withdrawn and spaces to which air is introducedmay be varied without departing from the teaching of the invention.Thus, in the embodiment of FIG. 8 air is introduced to a space adjacentto an end plate and withdrawn from a space adjacent the other end platewhereas in the embodiment of FIG. 9 air is introduced to each of the twospaces which are adjacent to the end plates and in the embodiment ofFIG. 10 air is withdrawn from each of the two spaces which are adjacentto the end plates. Likewise the embodiments of FIGS. 8, 9 and 10 showthat different numbers of such spaces, defined by end plates andbaffles, may be utilized in accordance with the invention.

Since in all embodiments, as has been mentioned, flow outward of gasfrom the ends of the bayonet tube is nil and flow of ambient air intothe ends of the bayonet tube is nil, the device may be operated with agas therein which is other than air, for example, nitrogen or hydrogen.

Referring now to FIG. 11, bayonet 250 may correspond to any one ofbayonets 46, 146 or 246 in that it comprises a tube provided with endplates and baffles attached thereto which define spaces thereinbetweenand which is received in shroud tube 251 which may correspond to shroudtube 232. Tube 251 may be provided with ports 252 through which air orother gas may be introduced or withdrawn into or from the definedspaces. Other portions of the apparatus such as housing, manifolding,blower and heater are omitted for simplicity. Vibrating device 253 maybe attached to shroud tube 251 or to any portion of the device such as ahousing or the like whereby, by operation of the device 253 in avibratory manner as indicated by arrow 254, it provides longitudinalvibration of shroud tube 251 and bayonet 250 as indicated by arrow 255.Such vibratory motion may serve to assist gravity in providing fortravel of articles to be heat treated through the tube within bayonet250 or may be the sole means providing for such travel if, for example,bayonet 250 and shroud tube 251 are disposed substantially horizontally.

The embodiment of FIG. 12 is provided with bayonet 250 (which may beidentical with bayonet 250 of FIG.

11) and shroud tube 251'. Tube 251'. may correspond to shroud tube 251exceptithat insteadof being cylindrical it may be provided withsuccessively wider and narrower portions to provide spaces between theend plates and baffles which are not of the cylindrical shape describedfor said spaces in the embodiments of FIGS. 1-7, 8, 9, l0 and 11. Ports252' may correspond to ports 252.

As indicated by the embodiment of FIG. 12,.spaces defined by the endplates and baffles need not be cylindrically annular but may be of anysuitable shape. The embodiment of FIG. 12 of course may be provided witha vibratory device in the same manner as that of FIG. 11 and of courseany one of the embodiments of FIGS. 1-10 may be provided with such adevice in the event that a vibratory motion is desired either to aloneprovide for travel of parts through the device or to provide assistancefor the force of gravity.

The apertures in tubes 13, 147 and 213 which provide for flow of gasbetween spaces defined by end plates and baffles and the interior of thetubes may have any suitable shape. Thus, they may be square as shown forapertures 131 in FIG. 8; they may have the form of slots as shown forapertures and 171 in FIG. 9; or they may be oval as exemplified byapertures 132 in FIG. 8.

In FIG. 13 there is shown a release mechanism 71 which is indicatedschematically in FIGS. 1-7. Mechanism 71 which may be mounted on a plate72 which may be attached to housing 20 by screws 73. In the releasemechanism, tube 270 may be mounted coaxially with and slightly spacedapart from end 36 of tube 13 and may have an inside diametersufficiently large to receive springs emerging from ends 36. Slot 271 isprovided in the wall of tube 270 near its upper end and, spaced apartdownwardly therefrom, aperture 272 may be provided in the wall of tube270. Aligned with slot 271 there may be provided a first solenoid 273containing magnetically susceptible mass 274 attached to pis-' ton orrod 275 slidably received in guide 276. Rod 275 may terminate in anenlarged end 277 which may be attached to member 278 which is providedwith a bore 279 to slidably receive rod 280 which is provided withenlarged head 281 which is received in cavity 282 in member 278. At theother end, rod 280 may be threadedly attached to shoe 283 which mayextend through slot 271 which may frictionally engage spring 284contained in tube 270 urging spring 284 against the opposite interiorwall of tube 270 and thereby preventing passage of spring 284 throughtube 270 due to the friction of the spring with said wall, shoe 283being urged against spring 284 by spring 285 contained within cavity 286in member 278 and bearing against shoulder 287 provided in member 278 atthe end of cavity 286. When solenoid 274 is actuated, slot 274 occupiesthe position shown in dashed lines at 274' and end 277 occupies theposition shown in dashed lines 277 and head 282 occupies the positionshown in dashed lines at 282', being urged against shoulder 288 ofcavity 282 by spring 285. The face of shoe 283 is disposed at theposition indicated in dashed lines at 283 because the motion to theright of slug 274 and rod 275 as indicated at 274 and 277 is designed tobe greater than the travel of rod 280 to the left. Spring 284 is thusreleased and may drop out of tube 270.

When solenoid 273 is de-energized, the movable portions are urged to theleft into the positions shown in full lines by compression spring 289acting against guide 276 to urge enlarged head 277 leftwards.

Solenoid 293 is attached to plate 72 in alignment with aperture 272 inthe wall of 270 and is provided with magnetically susceptible slug 294therewithin attached to rod 295 received slidably in guide 296. Needle297 is adapted to extend through aperture 272and as attached to rod 295.The positions of slug 294, rod 95 and needle 297 shown in full lines arethose occupied when solenoid 293 is energized. When solenoid 293 isde-energized, slug 294, rod 295 and needle 297 occupy the positionsshown in dashed lines at 294', 295 and 297' being moved leftwards by theurging of compression spring 298 acting against guide 296 and member 299attached to rod 295.

In operation, solenoid 273 is normally de-energized so that shoe 283occupies the position shown in full lines to retain a spring in tube 270and solenoid 293 is normally energized to provide needle-297 in theposition shown in full lines so that a spring may pass downwardly pastaperture 272 as indicated by falling spring 284'.

When a signal is received from member 70 indicating that a spring isentering end 35 of bayonet 46, a corresponding signal is transmitted byelectronic means, not shown for simplicity, to each of solenoids 273 and293 and solenoid 273 is energized and solenoid 293 is deenergized andaccordingly shoe 283 is disengaged with a spring contained in tube 270and needle 297 is thrust through aperture 272 into tube 270 so that itinterrupts and stops the downward motion of the spring released by shoe283. In this manner the entire column of springs contained within tube13 is allowed to drop a distance corresponding to the length of onespring and space is thus provided in the interior of tube 13 adjacentend 35 to receive the spring which caused device 70 to emit a signalindicating the presence of the spring.

Immediately thereafter solenoid 273 is again deenergized so that shoe283 again engages the spring now opposite it in the tube and solenoid293 is energized to withdraw needle 297 from tube 270 and allow thespring previously retained in tube 270 by needle 297 to drop from tube270 in the manner of spring 284'. The cycle is then of course repeatedeach time a spring enters the-device 70.

Release mechanism 71 shown in FIG. 14 corresponds to release mechanism71 and all parts therein and the function thereof may be as describedfor device 71 except that solenoids 273 and 293 and slugs 274 and 294are replaced respectively with double acting air or hydraulic cylinders300 and 301 which contain pistons attached respectively to rods 275 and295. By reason of each of cylinders 300 and 301 being double acting,rods 275 and 295 are positively driven to the left by cylinders 300 and301 as well as being positively driven to the right by cylinders 300 and301 so that springs 289 and 298 and member 299 may be omitted. Tubes forintroducing air or hydraulic fluid to cylinders 300 and 301 are omittedfor simplicity as are valves for controlling introduction of fluid tothe cylinders in response to a signal generated in response to thesignal from device lielease mechanisms 71" shown in FIG. 15 is similarto the embodiment 71 of FIG. 14 in that it is operated by a doubleacting air or hydraulic cylinder but otherwise it is appreciablydifferent. Tube 310, is attached to plate 272 in alignment with end 36of tube 13. Slidably treated in tube 13. Tube 311 may be'retainedin tube310 with thumb screw 312.

Since the bayonets may be changed to provide bayonets having tubes ofdifferent internal diameters, tube 311 may be replaced with any one ofseveralother tubes having greater or lesser diameter bores correspondingto the diameters of springs to be treated with different bayonets.

Upper aligned apertures 314 and 315 and lower aligned apertures 316 and317 are provided respectively in the walls of tubes 310 and 311. Block320 is attached to plate 72 and provided with a cavity 321 aligned withholes 314 and 315 and a cavity 322 aligned with holes 316 and 317.Threadedly received in cavity 321 is guide member 323 bored at 324 toslidably receive needle 325. In like manner guide member 326 isthreadedly received in cavity 322 and bored at 327 to slidably receiveneedle 328. Needles 325 and 328 may extend outside the block 320 throughholes .329 and 330 communicating with cavities 321 and 322.

Needle 325 is urged leftwardly by compression spring 331 acting betweenguide 323 and retainer member 332 attached to needle 325.

Needle 328 is urged leftwardly by compression spring 333 acting betweenguide member 326 and retainer member 334 attached to needle 328.

Pivotally attached to plate 72 at 335 there may be die 328 is forced tothe right by cam face 337 and projects into the interior of tube 31 1,preventing downward movement of spring 350 contained therewithin andlikewise all other springs disposed above spring 350 in the-device suchas spring 351, while needle 325 is withdrawn from tube 311.

Cylinder 343 may be operated to drive piston rod 342 to the positionshown in dashed lines at 342; whereupon link 340 and crank member 336occupy the positions shown in dashed lines at 340 and 336' and needles325 and 328 occupy the positions shown in dashed lines at 325 and 328,needle 325 being forced between springs 350 and 351 and needle 328 beingwithdrawn from the interior of tube 311 whereupon spring 350 is allowedto fall free from the device as indicated at 350' and spring 351 andsprings thereabove are retained in their present position by needle 325.

In operation, cylinder 343 is normally operated to provide crank 336 inthe position of 336' so that a spring corresponding to spring 351 isretained in the device and all springs extending upwardly through tube13 are retained in the device and any spring corresponding to spring 350is allowed to fall free from the device.

When a signal emitted by device 70 causes means not shown for simplicityto provide actuation of cylinder 343, cylinder 343 moves crank 336 tothe position shown in full lines which moves needle 328 to the positionshown in full lines and withdraws needle 325 to the position shown infull lines. The spring corresponding to spring 351 drops to the positionshown for spring 350, thus allowing all springs above it in the columnto drop correspondingly and thus providing space within tube 13 adjacentend 35 for the spring which has caused device 70 to emit a signal toenter tube 13.

Immediately thereafter cylinder 343 may be automatically operated tocause crank 336 to resume the position shown at 336 whereupon the springnonnally retained in the position of spring 351 continues to be retainedin place by the action of needle 325 thereunder and the spring recentlyallowed to fall to the position of spring 350 is allowed to fall free inthe manner shown at 350.

This cycle of events if of course repeated each time a spring entersdevice 70.

Each of curves 1, 2, 3 and 4 is a plot of the temperature within abayonet tube at various distances from the ends as indicated on theabscissa. Curves 1 and 2 show the temperature of one of the springs 360of FIG. 17 at various points in the tube of a bayonet designed to treatsuch springs, with the control temperature being set at 750F. Curve No.1 was obtained with the tube entirelyfull of springs as it would be inactual use but with the spring of which the temperature was measuredbeing allowed (and all the other springs above and below it beingallowed) to remain at each position until its temperature stabilized.Curve 2 was obtained in the same manner with the same spring but withoutother springs in the tube. Curves No. 3 and No. 4 are plots of thetemperature of one of springs 367 of FIG. 18 in a bayonet designed totreat these springs, with the bayonet tube entirely full of springs asin the case of curve No. l but with the control set for 600F. in thecase of curve No. 3 and 375F. in the case of curve No. 4.

Curve No. in FIG. 19 shows the rate of heat rise of one of springs 360of FIG. 17 when traveling through a bayonet tube designed to heat treatsaid springs (with other springs thereabove and therebelow in the mannerin which it travels in actual use), springs being treated per minute.The data for curve No. 5 was obtained with a bayonet tube about 30inches long. Accordingly 25 pieces were contained in the tube at any onetime, each spring being 1% inches long, and accordingly each springremained in the tube for approximately 15 seconds. The actual timeeachspring remained in the bayonet tube is shown as 17% seconds and theapproximate time each remained within the portion of the bayonet tubedisposed within the housing is shown as approximately 14% seconds.Control temperature was set at 750F. and it may be noted that eachspring reached its desired minimum heat treatment temperature of 700F.after about 9% seconds and was heated to approximately 750F. after about12% seconds and remained at a temperature of between 750F. and 650F. forapproximately 5% seconds or until it exited from the bayonet tube. Thusthe overall time during which the spring was subjected to atemperatureabove 700F. was on the order of 7 seconds, Q.

sufficient t o ac c o mplish the heat treating desired. v

Curves No. 6 and No. 7 were obtained with one of springs 361 of FIG. 18traveling through the tube of a bayonet designed for heat treatment ofsaid springs at a rate of 25 per minute, the bayonet tube being about 36inches long. The data of curve No. 6 were obtained with the controls setfor the desired heat treatment temperature of 600F. The data of curveNo. 7 were obtained with a control setting of 375F. for a desired heattreatment temperature of 375F. At the rate of 25 In connection withFIGS. l9'and 20, it may be noted that the time during which a spring hasbeen subjected to heat in the device is directly proportional to itsposition in the device. Thus, if it remains in the device 18 seconds,after 9 seconds it has traveled 50 percent of the way through thedevice. Accordingly, the time shown on the abssissae of FIGS. 19 and 20is correlated with the position of the spring in the device as indicatedby the legends indicating a point or time of entry into and exit fromthe bayonet tube and entry into and exit 9 e hay n As mentioned above,any bayonet in any of the embodiments shown may be readily removed andreplaced with another bayonet having a tube of greater or lesserinternal diameter and provided with apertures to provide suitable airflow for treating articles in such bayonet having a tube of greater orlesser internal diameter It will be apparent to those skilled in the artthat equivalents may be utilized.

Accordingly, the present invention may be embodied Y in other specificforms without departing from the spirit or essential attributes thereof,and accordingly, reference should be made to the appended claims ratherthan to the foregoing specification as indicating the scope of theinvention.

It is claimed: 1. In a device for heat treating small discrete metalarticles the combination of a bayonet, said bayonet comprising a tubularmember having an inlet end and an outlet end, said tubular member devoidof closure means at its ends, a first end plate extending from saidtubular member near its inlet end, a second end plate extending fromsaid tubular member near its outlet end,

at least three baffle members extending from said tubular member betweensaid first end plate and said second end plate,

a shroud tube, I

said bayonet slidably received in said shroud tube,

the outer peripheries of said end plates and said baffle members beingslidably engaged with the interior of said shroud tube,

said end plates and said baffle members defining spaces between theexterior of said tubular mem-' her and the interior of said shroud tube,

apertures in the wall of said tubular member communicating its interiorwith a plurality of said. defined spaces,

blower means and heater means to provide heated gas having an elevatedtemperature and a substantial pressure and velocity,

means to introduce said heated gas into a plurality of said definedspaces, and

means to withdraw said heated gas from a plurality of said definedspaces,

duct means to cycle said withdrawn gas to said blower means and thenceto said spaces into which said gas is introduced. 2. The device of claim1 wherein first, second, third and fourth baffle members are providedand the first baffle member is the nearest baffle member to said firstend plate and said fourth baffle member is the nearest baffle member tosaid second end plate and said first end plate and said first bafflemember provide a first space between the exterior of said tubular memberand the interior of said shroud tube,

said first baffle member and said second baffle mem ber provide a secondspace between the end of said tubular member and the interior of saidshroud tube,

said second bafile member and said third baffle member provide a thirdspace between the end of said tubular member and the interior of saidshroud tube,

said third baffle member and said fourth baffle member provide a fourthspace between the end of said tubular member and the interior of saidshroud tube, said fourth baffle member and said second end plate providea fifth space between the end of said tubular member and the interior ofsaid shroud tube, and wherein duct means is attached to said shroud tubeto provide for introduction of said heated gas into said second andfifth spaces, g 1

duct means is attached to said shroud tube to provide for withdrawal tosaid blower means of gas from said first and fourth spaces,

apertures are provided in said second and third baffle members forpassage of gas from said second space M to said third space and fromsaid third space to said fourth space, apertures are provided in thewall of said tubular member to provide for gas flow from the interior ofsaid tubular member to said first and fourth spaces,

and apertures are provided in the wall of said tubular member to providefor gas flow from said second and fifth spaces into the interior of saidtubular JE QQEE r, r, t

3. The device of claim 1 characterized by the spacing of said end platesand baffle members and the spacing and locations and size of saidapertures in said tubular member being preselected to provide niloutflow of gas from said tubular member at its ends and nil inflow of29% into sa d. t ul rmemb at its 292,

4. The device of claim 3 further characterized by means to sense thepresence of a part to be heat treated adjacent to said inlet end of saidtubular member and to generate and emit a signal in response to saidpresence of such part.

5. The apparatus of claim 4 further characterized by means adjacent tothe outlet end of said tubular member to sequentially release a partfromsaid device in response to a signal generated by said signal emittedby the means of claim 3.

6. The device of claim 3 wherein first, second, third and fourth bafflemembers are provided and the first baffle member is 'thenearest bafflemember to said first end plate and said fourth-baffle member is thenearest baffle member to said second end plate and said first end plateand said first baffle member provide a first space between the exteriorof said tubular member and the interior of said shroud tube, said firstbaffle member and said second baffle member provide a second spacebetween the end of said tubular member and the interior of said shroudtube, said second baffle member and said third baffle member provide athird space between the end of said tubular member and the interior ofsaidshroud tube, said third baffle member and said fourth baffle memberprovide a fourth space between the end of said tubular member and theinterior of said shroud tube, said fourth baffle member and said secondend plate provide a fifth space between the end of said tubular memberand the interior of .said shroud tube,..

and wherein duct means is attached to said shroud tube to provide 1 forintroduction of said heated gas into said second and fifth spaces,

duct means is attached to said shroud tube to provide for withdrawal tosaid blower means of gas from said first and fourth spaces, I aperturesare provided in said second and third baffle members for passage of gasfrom said second space and fifth spaces into the interior of saidtubular member.

7. The device of claim 6 further characterized by means to sense thepresence of a part to be heat treated adjacent to said inlet end of saidtubular member and to generate and emit a signal in response to saidpresence of such part.

8. The apparatus of claim 7 further characterized by means adjacent tothe outlet end of said tubular member to sequentially release a partfrom said device in response to a signal generated by said signalemitted by the means of claim 3.

9. The method of heat treating a plurality of springs characterized bythe combination of steps of:

orienting a plurality of springs end-to-end in a downwardly extendingstack,

releasing a spring from the bottom of the stack to cause the stack tofall a distance equal to the length of one spring each time a spring isabout to be added to the top of the stack, dividing the stack into aplurality of zones, introducing heated gas to a plurality of said zones,withdrawing said heated gas from a plurality of said zones, and causingsaid gas to flow around the springs in said stack with high velocityturbulent flow generally longitudinally with respect to said stackbetween each of said zones.

10. The method of claim 9 wherein said stack is enclosed, characterizedby the step of providing flow rates into and out of and between saidzones at preselected values to provide for nil outflow from the stack ofheated gas at the ends of the stack and nil inflow to the stack ofambient air at the ends of the stack.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No.3,850,572. Dated N VGIT BBI 26, 1974 lnventofls) Everett Howard AndrusIt is certified that error appears in the above-identified patent andthat said Letters Patent are hereby corrected as shown below: 0

Column 5, line 23, "welldments" should read weldments Column 9, line 18,"solenoid 274" should read solenoid Q 273 Column 10, line 26,"mechanisms" should read mechanism Column 11, line 44, "if" should readis line 64, "375'P.""should read 375F. Column 14,

a line 15, "locations" should read location a, line 27,

"claim 3" should read claim 4 1. Column 15, line l2 "claim 3" shouldread claim 7 1-. Q En'gncd and Scaled this twenty-sixth Day 0f August1975 [SEAL] Arrest:

RUTH c. MASON c. MARSHALL DANN Arresting Officer Commissioner uflatentsand Trademarks FORM PO-IOSO (10-69) USCOMM'DC 60376-P69 U15. GOVERNMENTPRINTING OFFICE: 8 I 9- 9

1. In a device for heat treating small discrete metal articles thecombination of a bayonet, said bayonet comprising a tubular memberhaving an inlet end and an outlet end, said tubular member devoid ofclosure means at its ends, a first end plate extending from said tubularmember near its inlet end, a second end plate extending from saidtubular member near its outlet end, at least three baffle membersextending from said tubular member between said first end plate and saidsecond end plate, a shroud tube, said bayonet slidably received in saidshroud tube, the outer peripheries of said end plates and said bafflemembers being slidably engaged with the interior of said shroud tube,said end plates and said baffle members defining spaces between theexterior of said tubular member and the interior of said shroud tube,apertures in the wall of said tubular member communicating its interiorwith a plurality of said defined spaces, blower means and heater meansto provide heated gas having an elevated temperature and a substantialpressure and velocity, means to introduce said heated gas into aplurality of said defined spaces, and means to withdraw said heated gasfrom a plurality of said defined spaces, duct means to cycle saidwithdrawn gas to said blower means and thence to said spaces into whichsaid gas is introduced.
 2. The device of claim 1 wherein first, second,third and fourth baffle members are provided and the first baffle memberis the nearest baffle member to said first end plate and said fourthbaffle member is the nearest baffle member to said second end plate andsaid first end plate and said first baffle member provide a first spacebetween the exterior of said tubular member and the interior of saidshroud tube, said first baffle member and said second baffle memberprovide a second space between the end of said tubular member and theinterior of said shroud tube, said second baffle member and said thirdbaffle member provide a third space between the end of said tubularmember and the interior of said shroud tube, said third baffle memberand said fourth baffle member provide a fourth space between the end ofsaid tubular member and the interior of said shroud tube, said fourthbaffle member and said second end plate provide a fifth space betweenthe end of said tubular member and the interior of said shroud tube, andwherein duct means is attached to said shroud tube to provide forintroduction of said heated gas into said second and fifth spaces, ductmeans is attached to said shroud tube to provide for withdrawal to saidblower means of gas from said first and fourth spaces, apertures areprovided in said second and third baffle members for passage of gas fromsaid second space to said third space and from said third space to saidfourth space, apertures are provided in the wall of said tubular memberto provide for gas flow from the interior of said tubular member to saidfirst and fourth spaces, and apertures are provided in the wall of saidtubular member to provide for gas flow from said second and fifth spacesinto the interior of said tubular member.
 3. The device of claim 1characterized by the spacing of said end plates and baffle members andthe spacing and location and size of said apertures in said tubularmember being preselected to provide nil outflow of gas from said tubularmember at its ends and nil inflow of ambient air into said tubularmember at its ends.
 4. The device of claim 3 further characterized bymeans to sense the presence of a part to be heat treated adjacent tosaid inlet end of said tubular member and to generate and emit a signalin response to said presence of such part.
 5. The apparatus of claim 4further characterized by means adjacent to the outlet end of saidtubular member to sequentially release a part from said device inresponse to a signal generated by said signal emitted by the means ofclaim
 3. 6. The device of claim 3 wherein first, second, third andfourth baffle members are provided and the first baffle member is thenearest baffle member to said first end plate and said fourth bafflemember is the nearest baffle member to said second end plate and saidfirst end plate and said first baffle member provide a first spacebetween the exterior of said tubular member and the interior of saidshroud tube, said first baffle member and said second baffle memberprovide a second space between the end of said tubular member and theinterior of said shroud tube, said second baffle member and said thirdbaffle member provide a third space between the end of said tubularmember and the interior of said shroud tube, said third baffle memberand said fourth baffle member provide a fourth space between the end ofsaid tubular member and the interior of said shroud tube, said fourthbaffle member and said second end plate provide a fifth space betweenthe end of said tubular member and the interior of said shroud tube, andwherein duct means is attached to said shroud tube to provide forintroduction of said heated gas into said second and fifth spaces, ductmeans is attached to said shroud tube to provide for withdrawal to saidblower means of gas from said first and fourth spaces, apertures areprovided in said second and third baffle members for passage of gas fromsaid second space to said third space and from said third space to saidfourth space, apertures are provided in the wall of said tubular memberto provide for gas flow from the interior of said tubular member to saidfirst and fourth spaces, and apertures are provided in the wall of saidtubular member to provide for gas flow from said second and fifth spacesinto the interior of said tubular member.
 7. The device of claim 6further characterized by means to sense the presence of a part to beheat treated adjacent to said inlet end of said tubular member and togenerate and emit a signal in response to said presence of such part. 8.The apparatus of claim 7 further characterized by means adjacent to theoutlet end of said tubular member to sequentially release a part fromsaid device in response to a signal generated by said signal emitted bythe means of claim
 3. 9. The method of heat treating a plurality ofsprings characterized by the combination of steps of: orienting aplurality of springs end-to-end in a downwardly extending stack,releasing a spring from the bottom of the stack to cause the stack tofall a distance equal to the length of one spring each time a spring isabout to be added to the top of the stack, dividing the stack into aplurality of zones, introducing heated gas to a plurality of said zones,withdrawing said heated gas from a plurality of said zones, and causingsaid gas to flow around the springs in said stack with high velocityturbulent flow generally longitudinally with respect to said stackbetween each of said zones.
 10. The method of claim 9 wherein said stackis enclosed, characterized by the step of providing flow rates into andout of and between said zones at preselected values to provide for niloutflow from the stack of heated gas at the ends of the stack and nilinflow to the stack of ambient air at the ends of the stack.